N,n,n{40 ,n{40 -tetrakis-(p-di acyclic hydrocarbyl-amino-phenyl)-p-arylenediamine

ABSTRACT

Diaryl-(N,N-diarylaminoaryl)aminium salts represented by the formula: WHEREIN A, B, D, E and F represent bivalent benzene or bivalent naphthalene radicals; n is 1 or 2; R, R1, R2 and R3 represent hydrogen, alkyl, alkoxy, alkenyl, aralkyl, aryl, alkaryl, acyl or RADICALS, SAID R4 and R5 in turn representing hydrogen, alkyl, alkenyl, aralkyl, aryl, alkaryl or acyl radicals; said A, B, D, E and F and R through R5 which are other than hydrogen being either unsubstituted or substituted with inert groups such as lower alkyl, lower alkoxy, hydroxy, cyano, carboxy, sulfo, halogen and the like; and X represents an anion; are useful as infrared absorbers. Illustrative species of the aminium salts are (1) bis(p-diethylaminophenyl)(N,N-bis(p-diethylaminophenyl)-paminophenyl)aminium hexafluoroarsenate, (2) bis(pethylaminophenyl)(N,N-bis(p-ethylaminophenyl)-p-aminophenyl)aminium hexafluoroarsenate, (3) bis(pdiethylaminophenyl)(N,N-bis(p-diethylaminophenyl) -4&#39;&#39;aminobiphenylyl)aminium hexafluoroarsenate and (4) bis(4-(bis(2hydroxyethyl)amino)phenyl)-(N,N-bis(4 -(bis(2hydroxyethyl)amino)phenyl)-4-aminophenyl)aminium hexafluoroantimonate. The salts are made by reacting the appropriate N,N,N&#39;&#39;,N&#39;&#39;-tetrakis(p-dialkylaminophenyl)-pphenylenediamine with an appropriate silver salt. For example, salt (1) above is made by reacting N,N,N&#39;&#39;,N&#39;&#39;-tetrakis(pdiethylaminophenyl)-p-phenylenediamine with silver hexafluoroarsenate in a solvent, such as dimethylformamide or acetone, and cooling the reaction mixture to precipitate the product salt. The intermediate N,N,N&#39;&#39;,N&#39;&#39;-tetrakis(pdialkylaminophenyl)-p-phenylenediamine compounds are formed, for example, by reacting p-nitrohalobenzene with p-phenylenediamine to form N,N,N&#39;&#39;,N&#39;&#39;-tetrakis(p-nitrophenyl)-p-phenylenediamine, followed by reduction of the nitro groups to amino groups by hydrogenation in the presence of a catalyst, such as palladium on charcoal, and alkylation of the amino groups with an alkylating agent, such as an alkyl halide. The aminium salts, which absorb broadly in the near-infrared region, may be incorporated into various materials to increase the infrared absorption thereof. A preferred use is the incorporation of the salts into plastics from which optical lenses for sunglasses, welders&#39;&#39; goggles and the like are made, such lenses affording protection to the eye against infrared radiation.

United States Patent Susi et al.

[ 1 June 13, 1972 [72] Inventors: Peter Vincent Susi, Middlesex; Norma Ann Weston, Somerville, both of NJ.

[73] Assignee: American Cyanamid Company, Stamford,

Conn.

[22] Filed: Dec. 6, 1968 [21] Appl. No.1 781,973

Related US. Application Data [60] Division of Ser. No. 607,390, Jan. 5, 1967, Pat. No. 3,484,467, which is a continuation-in-part of Ser. No.

333,728, Dec. 26, 1963, abandoned, which is a continuation-in-part of Ser. No. 281,056, May 16, 1963,

Primary Examiner-Henry R. .liles Assistant Examiner-C. F. Warren Atl0rneyJohn L. Sullivan [5 7] ABSTRACT Diaryl-(N,N-diarylaminoaryl)aminium salts represented by the formula:

wherein A, B, D, E and F represent bivalent benzene or bivalent naphthalene radicals; n is l or 2; R, R R and R represent hydrogen, alkyl, alkoxy, alkenyl, aralkyl, aryl, alkaryl, acyl or radicals, said R, and R in turn representing hydrogen, alkyl, alkenyl, aralkyl, aryl, alkaryl or acyl radicals; said A, B, D, E and F and R through R, which are other than hydrogen being either unsubstituted or substituted with inert groups such as lower alkyl, lower alkoxy, hydroxy, cyano, carboxy, sulfo, halogen and the like; and X" represents an anion; are useful as infrared absorbers. Illustrative species of the aminium salts are l bis( p-diethylaminophenyl)[N,N-bis( p-diethylaminophenyl)-p-aminophenyl]aminium hexafluoroarsenate, (2) bis(pethylaminophenyl [N ,N-bis( p-ethylaminophenyl )-p-aminophenyl ]aminium hexafluoroarsenate, (3) bis( pdiethylaminophenyl)[N,N-bis(p-diethylaminophenyl)-4- aminobiphenylyHaminium hexafluoroarsenate and (4) bis( 4- [bis( 2-hydroxyethyl )amino ]phenyl N,N-bis( 4- bis( 2- hydroxyethyl)amino]phenyl)-4-aminophenyl]aminium hexafiuoroantimonate. The salts are made by reacting the appropriate N,N,N,N'-tetrakis(p-dialkylaminophenyl)-p-phenylenediamine with an appropriate silver salt. For example, salt (1) above is made by reacting N,N,N',N'-tetrakis(pdiethylaminophenyl)-phenylenediamine with silver hexafiuoroarsenate in a so vent, such as dimethylformamide or acetone, and cooling the reaction mixture to precipitate the product salt. The intermediate N,N,N,N-tetrakis(p-dialkylaminophenyl)-p-phenylenediamine compounds are formed, for example, by reacting p-nitrohalobenzene with pphenylenediamine to form N,N,N,N'-tetrakis(p-nitrophenyl)-p-phenylenediamine, followed by reduction of the nitro groups to amino groups by hydrogenation in the presence of a catalyst, such as palladium on charcoal, and alkylation of the amino groups with an alkylating agent, such as an alkyl halide. The aminium salts, which absorb broadly in the near-infrared region, may be incorporated into various materials to increase the infrared absorption thereof. A preferred use is the incorporation of the salts into plastics from which optical lenses for sunglasses, welders goggles and the like are made, such lenses affording protection to the eye against infrared radiation.

5 Claims, No Drawings N,N,N ,N-TETRAKIS-(P-DI ACYCLIC HYDROCARBYL- AMINO-PHENYL)-P-ARYLENEDIAMINE This application is a divisional of application, Ser. No.

607,390, filed Jan 1967, HOW ,4 4,4 5 the compounds (of Formula II) are prepared by a series of sued Dec. 16, 1969 which, in turn, is a continuation-in-part of application, Ser. No. 333,728, filed Dec. 26, 1963, now abandoned, which, in turn, is a continuation-in-part of application, Ser. No 281,056, filed May 16, 1963, now abandoned.

This invention relates to a new class of aminium salts and to the use of said salts as infrared absorbers. It also relates to a process for making said salts and to a series of new compounds which are intermediates in said process.

The new aminium salts of the invention are represented by the following formula:

wherein A, B, D, E and F represent bivalent benzene or bivalent naphthalene radicals; n is l or 2; R, R R and hydrogen, alkyl, alkoxy, alkenyl, aralkyl, aryl, alkaryl, acyl or wherein A, B, D, E and F and R through R,, have the same meaning as in Formula I, by the oxidation of one of the amino groups thereof to form the aminium cation, as described hereinafter,

The compounds of Formula II may be prepared as follows. On the one hand, a compound having the formula (III) I 2N L.A. I NH:

wherein A has the same means as in Formulas I and I] is reacted with a substituted or unsubstituted halobenzene or halonaphthalene, any substituent present therein being any one of those within the definition of R, R R or R, given above in connection with Formulas] and 11, except A typical reaction is that of a halobenzene and p-phenylenediamine, as follows.

i alkali (A cmupouml of l-unuulu ll) l alkali (Compounds of Formula II) II2N In reaction (3), R2 represents an alkylating agent in which R corresponds to R or R in Formula II. Suitable RZ compounds are set forth hereinbelow.

Reactions 1 and (la) are carried out in a suitable solvent, preferably dimethylformamide, in the presence of an alkali, such as sodium or potassium carbonate and optionally and preferably in the presence of copper powder. The reactions can be effected in a step-wise fashion, so that from one to four of the amino hydrogens (of the diamine) are replaced, thereby permitting preparation of unsymmetrical derivatives.

With respect to reaction (1), illustrative halobenzenes which may be used include, for example, iodobenzene, bromobenzene, p-iodotoluene, o-iodotoluene, mbromotoluene, p-iodododecylbenzene, p-iodoallylbenzene, 4- bromodiphenylmethane, 4-bromodiphenyl, 4- iodoacetophenone, 4-bromobenzophenone, 3-bromoanisole, etc.

Also, utilizable halonaphthalenes include 1- iodonaphthalene, 2-bromonaphthalene, l-bromo-4-methylnaphthalene, -bromo-4-butoxynaphthalene, l-bromo-4- ethynaphthalene, 1-iodo-6-methoxynaphthalene, etc.

With respect to reaction (1a nitro-substituted halobenzenes which may be used include o-, mand pnitrohalobenzenes, such as p-nitrochlorobenzene, mnitrochlorobenzene, p-nitrobromobenzene, onitroiodobenzene, p-nitrofluorobenzene, 3,4- dichloronitrobenzene, 2-chloro-5-nitrotoluene, 2-chloro-5- nitroethylbenzene, 2-nitro-5-bromotoluene, 2-chloro-5- nitroanisole and the like.

Compounds of Formula III utilizable in both reactions (1) and (la) include phenylenediamines, biphenyldiamines, naphthalenediamines and bi(naphthylamines). Illustrative phenylenediamines include p-phenylenediamine, o-phenylenediamine, m-phenylenediamine, p-toluylenediamine, 2,5- dimethoxy-p-phenylenediamine, 2,6-dimethyl-p-phenylenediamine, etc. Illustrative biphenyldiamines include benzidine, 2,2'-biphenyldiamine, 3,3'-biphenyldiamine, 2,4- diphenyldiamine, 6,6'-dimethyl-2,2-biphenyldiamine, otolidine, o-dianisidine, m-tolidine, etc. Illustrative naphthalenediamines include l,4-naphthalenediamine, 1,5- naphthalenediamine, 2,6-naphthalenediamine, 2-ethoxy-l,4- naphthalenediamine, 2-ethyl-1,4-naphthalenediamine, 4,8-

dimethoxy-Z,-naphthalenediamine, etc. Illustrative bi(naphthylamines) include naphthidine, 4,4'-bi( 2- naphthylamine), l ,1 -diethoxy-4,4-bi(2-naphthylamine), 2,2- bi-( l-naphthylamine), 2,4-bi( l-naphthylamine), 2,2- diamino-4,4 -bil -naphthol, etc.

Reduction of the nitrocompound (Reaction 2) is eflected conveniently by catalytic hydrogenation in a suitable solvent, again preferably dimethylformamide. Standard catalysts for the hydrogenation of aromatic nitro compounds may be used. These include palladium on charcoal and Raney nickel.

The amino compound from Reaction 2 is then reacted in a suitable solvent, such as aqueous acetone, with the reactant RZ according to Reaction 3. RZ may be a straight or branched chain alkyl halide, such as methyl chloride, ethyl iodide, propyl bromide, butyl iodide, hexyl bromide, octyl bromide, dodecyl bromide or a carboxy-substituted alkyl halide, such as chloroacetic acid; or an alkyl sulfate, such as methyl sulfate, ethyl sulfate and the like; or an alkyl arylsulfonate, such as methyl p-toluenesulfonate. An allyl halide, such as allyl bromide, also may be used. Other alkylating agents which may be used include acrylonitril and alkylene oxides, such as ethylene oxide. An alkali or alkaline salt such as sodium carbonate or potassium carbonate also normally is used. Reaction proportions and conditions are so selected that either one or two R" groups per amino group are introduced.

As has been indicated previously, the aryl rings of Formula I may bear inert substituents, such as lower alkyl or alkoxy. These substituted products may be derived from the corresponding substituted starting materials of halobenzenes or naphthalenes or the nitrosubstituted halobenzenes or naphthalenes in Reactions 1 and la. As also indicated previously, certain of the intermediate compounds, viz., those of the type formed in reactions 1 and 3 are believed to be new compounds.

Conversion of the compounds of reactions 1 or 3 to the salts of Formula I is efiected by oxidation of the amino compounds. This reaction is carried out in organic solvent solution by reacting the (polyamino) compound of Formula [I with a silver salt of a suitable acid. This general method is shown in Neunhoeffer et al., Ber. 92, 245 (1959). Dimethylformamide is a good solvent for use as the reaction medium. Others, such as acetone may be used. A wide variety of silver salts may be used. These include the perchlorate (ClOf), fluoborate (BFf), trichloracetate (CClfCOO), trifluoroacetate (CF COO), picrate, hxafluoroarsenate (AsF hexafluoroantimonate (SbF benzenesulfonate (C l-1 80 ethanesulfonate (C l-I SO phosphate (PO., sulfate 80 1), chloride (Cl) and the like.

Various aminium compounds such as tris(p-dialkylaminophenyl)aminium salts previously have been proposed for use in various substrates to decrease transmission in the infrared region of the spectrum. Such salts do absorb strongly in the near infrared region of the spectrum. However, most effective protection occurs in the vincinity of 960 millimicrons. Suitable compounds capable of broad absorption at longer wavelengths in the near infrared have been desired but in the past have not been available. It is, therefore, a principal object of the present invention to provide compounds having such broader absorption bands.

ln accordance with the present invention this object is accomplished by use of compounds of Formula I. Compounds of this invention absorb broadly in the near infrared region of the spectrum at wavelengths longer than those obtained with compounds previously available. Improved absorption is obtained in the region of longer wavelengths between about l,000 and about 1,800 millimicrons. Many of the compounds also have desirable absorption at shorter wavelengths in the near infrared region. These compounds also transmit a useful amount of visible light.

Radiant energy from the sun is frequently grouped into three regions, the near-ultraviolet, the visible and the near-infrared. Together these three regions cover the range of wavelengths of from 0.290 micron to about 5.0 microns.

Somewhat arbitrarily, the nearultraviolet spectrum may be considered to cover the region of 0300-0400 micron; the visible spectrum, the region of 0400-0700 micron; and the near-infi-ared spectrum the region of 0.7005.0 microns.

Heat from the sun is essentially due to the near-infrared radiant energy. Other high temperature bodies, such as tungsten filaments, fluorescent lamps, carbon arcs, etc., also radiate energy in the near infrared region. For practical purposes, this region often is defined as falling between 0.7 and 5.0 microns, this being the region where common sources of infrared radiation emit substantially all of their infrared energy. Over half of the total radiation energy emitted by the sun or electrical lamps lies in the near-infrared region. This is shown in the following tables.

TABLE L-APPROXIMATE DISTRIBUTION OF RADIANT ENERGY FROM SEVERAL ENERGY SOURCES Percent of total radiant energy emitted .Zl-AJ-l A m? .fi-Lfip. ADOVE .Tp

Sunlight (reaching earth) 5 42 54 53 Tungsten lamp, 500 w (J. 1 10 53 00 Flourescent lamp 5 35 28 60 Carbon filament heater 0 l 28 9!? Nonlumlnous heaters 0 0 1.3

Accordingly, it may be seen that a large proportion of the energy transmitted by our common light sources serves no useful purpose with respect to illumination, but contributes to the development of heat in the material receiving the radiation.

TABLE ll Approximate Distribution of Radiant Energy of Sunlight This table indicates that within the near-infrared region, the greater part of the infrared energy is radiated within the region from about 0.7 to about 2.0 microns. For example, in normal sunlight some two-thirds of the radiant energy is at wavelengths of from about 0.7 to about 1.3 microns.

it also may be noted in Table II that some 43-44% of the total infrared radiation in sunlight is in the region just above about 0.7 microns. The latter is about the upper limit of the visible range which, as noted above, usually is defined as from about 0.4 to about 0.7 microns, hence the near" infrared designation. While by the foregoing definition the near-infrared region extends only down to about 0.7 micron, for purposes of this invention the region of particular interest extends from about 0.65 micron to about 1.3 microns. In the following discussion this region will be designated as the (NIR).

In many circumstances it is desirable to filter out nonvisible radiations of the near-infrared region without materially diminishing transmission of visible radiations. There are many potential applications for materials that will transmit a major portion of the visible radiations but at the same time be at least semiopaque to heat-producing infrared radiation, particularly that in the above-noted (NIR). Among such possible applications may be mentioned sunglasses, welders goggles and other eye protective filters, windows, television filters, projection lenses and the like. In many, if not most, of such uses the primary object is to protect the human eye from the adverse effects of radiation in the near infrared.

Experience has shown that sunglasses, as an illustrative example, should be capable of transmitting at least about of incident visible light shorter than about 0.65 micron. However, to provide adequate protection for the human eye, transmission should be less than 40 at from about 0.65 to about 0.75 micron and not over about 10% between about 0.75 and about 0.95 micron. Preferably, some or more of visible light will be transmitted. In the two other noted ranges, preferably transmission should not exceed about 5% and 1% respectively.

Other protective optical filters may vary as to requirements in the visible range. In most cases, however, transmission in the near-infrared should not exceed the indicated limitations. This applies, for example, not only to other eye protective devices as widely different as welders goggles and window glass, but also to protecting inanimate material as in the case of projection lenses. Optimum protective utility, therefore, ordinarily requires relatively good transmission of radiation below about 0.65 micron but reduced or minimized transmission above that value. Obviously complete cutoff at exactly this, or any other wavelength, is impossible. Nevertheless, for the purposes of this invention, cutoff should be as sharp as possible within a minimum spread of wavelength at about 0.65 micron.

Various organic plastic substrates are available having generally suitable transmission properties in the visible region. Illustrative examples include: cellulose derivatives such as cellulose nitrate, cellulose acetate and the like; regenerated cellulose and cellulose ethers as for example, ethyl and methyl cellulose; polystyrene plastics such as polystyrene per se and polymers and copolymers of various ringsubstituted styrenes such for example as o-, mand pmethylstyrene and other ring-substituted styrenes as well as side chain substituted styrenes such as alpha-, methyland ethylstyrene and various other polymerizable and copolymerizable vinylidenes; various vinyl polymers and copolymers such as polyvinyl butyral and other acetals, polyvinyl chloride, polyvinyl acetate and its hydrolysis products, polyvinyl chloride-acetate copolymers and the like; various acrylic resins such as polymers and copolymers of methyl acrylate, methyl methacrylate, acrylamide, methylolacrylamide, acrylonitrile and the like; polyolefins such as polyethylene, polypropylene and the like; polyesters and unsaturated-modified polyester resins such as those made by condensation of polycarboxylic acids with polyhydric phenols or modified using unsaturated carboxylic acid and further modified by reacting the alkyd with another monomer; polymers of allyl diglycol carbonate; and various copolymers using as a cross-linking monomer an allyl ester of various acids. Of particular interest and preferred herein as substrates are cellulose acetate, methyl methacrylate, polystyrenes and polymers of allyl diglycol carbonates.

Any one such substrate may, and usually does, vary from the others very appreciably in its transmission of radiant energy at various wavelengths. Nevertheless, if not modified, none meet the foregoing transmission requirements. Some additive is necessary to decrease the infrared transmission without adversely effecting transmission in the visible range.

Heat resistance of the salts of this invention can be demonstrated when the aminium salts are dispersed in plastic materials, or when they are dissolved in suitable solvents. They are adequately resistant to exposure to temperatures up to about 200 C. This temperature is frequently encountered in the processing of plastic substrates such as those discussed above. Accordingly, compounds of this invention are suitable for purposes of use in such cases.

Products of this invention have good light and heat stability when incorporated into organic plastic substrates. Satisfactory absorption by transparent plastics of radiant energy in the 1,000 to 2,000 millimicron region (as given off by the sun or by other light sources) has not been possible heretofore. This portion of infrared radiation is a sizable portion of the total infrared radiation from sunlight, incadescent and other lamps.

In use, the salts of the resent invention may be incorporated in any suitable plastic or applied on suitable transparent substrates of plastic or glass. This is done by any of several known procedures, including for example; solution casting or dipping; hot milling; burnishing; or by dyeing. Organic plastic material containing the salts can be molded into formed articles such as sheets and plates.

In any method of use, the salts may be incorporated as a barrier layer in or near one surface of a substrate or be disseminated therethrough. Choice of either practice depends on the type of protection used and the physical method used to combine the substrate and the salt or salts.

Either practice can be used to protect the treated material. Either can also be used to form a protective barrier between an object to be protected and the source of the infrared radiation. In the latter case, protection is usually provided by combining salt and organic substrate in a relatively thin layer or sheet which is then used as the protective barrier. Protection of an object also can be obtained by coating the salts, in a suitable vehicle, directly onto substrates such as glass or formed plastic objects whether to protect the substrate or in forming a protective barrier for other objects.

It is not readily possible to assign limits to the amount which it is desirable to use. In general, the limiting maximum is only an economic one. As to the minimum, it depends on whether the salt is disseminated uniformly through the substrate or is concentrated in a barrier layer of the same or a different substrate. When disseminated through a substrate, usually to protect the latter, there should be provided at least about 0005 Weight percent of the substrate. When concentrated in a barrier layer this is equivalent to about 0.0] gram per square foot of surface of a plastic substrate of one-eighth inch thickness.

The compounds of this invention have many uses arising from the valuable combination of infrared absorbency and transparency to visible light. These uses may be considered as falling within three major areas according to the function of the infrared absorber.

In the first area of use, these compounds function to filter or screen out infrared radiation and prevent its transmission through a substrate on or in which these compounds are dispersed. In this area, specific applications are in sunglasses, welders goggles or shields, astronauts face-plates, and faceplates in fire-fighters reflective protective suits where transparency for vision coupled with protection of eyes from infrared radiation are desired. Also, these compounds may be incorporated in transparent plastic sheets or films for windows, doors, sky-lights, etc. in buildings, greenhouses, automobiles, aircraft, ships, etc. to screen out infrared radiation and minimize heat build-up in the interiors of such structures while still transmitting visible radiation. In such applications, these compounds may be dispersed in or on a rigid plastic substrate or may be dispersed in a thin plastic film useable alone or adhered to an untreated substrate, which may be glass or plastic. For example, for automobile safety glass Windshields,

the plastic interlayer between the two sheets of glass may have the infrared absorber incorporated therein. Also, for store, of fice, or residential windows, a plastic film containing these compounds may be adhered to the glass or may be hung as a window shade" immediately inside the window and rolled up when not needed. For sunglasses, aircraft windows, and skylights, these compounds may be incorporated in the plastic of which such articles are made, either as a uniform dispersion throughout or as a barrier layer adjacent one surface thereof.

In the second area of use, these compounds function to absorb infrared radiation and accumulate function to absorb infrared radiation and accumulate it as heat in order to increase the temperature of those materials containing these com pounds. Thus, these compounds can be incorporated onto natural or synthetic fibers used in clothing to make such clothing warmer in cold climates even though such clothing may be light in color. Also, these compounds can be dissolved in water or incorporated in plastic particles, flakes, or film strips which float on water to increase the rate of evaporation of the water (or other liquid) by solar or other infrared radiation for production of distilled water or for increasing salt concentration in the remaining liquor or for recovery of salt from solution. Further, these compounds can be incorporated into materials to improve drying rates without substantially changing the color of such materials, as, for example, colored inks, paints, enamels, bathing suits, etc. Likewise, incorporation of these compounds into polymerizable materials can serve to increase the rate of polymerization under infrared radiation by increasing the efficiency with which such radiation is absorbed. Also, since different colors absorb radiation at different rates, varying amounts of these compounds can be added to inks, paints, or enamels of various colors to so modify their drying rates as to make them uniform regardless of color for ease, uniformity, and economy in processing articles coated therewith.

Several processes currently in commercial operation use powdered ink formulations which are placed on paper or other substrate and fused in place by infrared radiation. In some reproduction and copying systems, the powdered ink formulations, which comprise carbon black (for infrared absorption capability and optical contrast with background) and thermoplastic polymer resins, are electrostatically attracted to the desired location either on metal and then transferred to paper or directly on specially coated paper. In such processes, only black inks have been useable to date. The present compounds can provide the necessary infrared absorption while permitting pigments of various colors to be used in such processes. Also, powdered inks are used to provide a raised printing on greeting cards, match boxes, calling cards, etc. by a process which involves printing a design on paper with a clear adhesive mixture and then coating with the powdered ink which adheres only to the adhesive-printed areas. This paper is then passed under an infrared source to melt and thus fix the ink. Incorporation of these compounds into these inks can reduce the heat required in the infrared source, increase the speed with which the inks can be fused, permit a wider range of colors to be used without danger of scorching the paper background before the powdered ink is set, and permit use of light colored inks on dark colored background paper without scorching the dark paper.

Some phototherrnography systems of photoreproduction, such as the Thermofax" system of copying, use a paper coated to make it more heat sensitive during the development of the image by exposure to infrared radiation. Incorporation of these compounds into the surface coating of the paper used for this and similar processes would make the paper even more heat sensitive without losing contrast between the printing and background making feasible lower operating temperatures or faster operation of copying devices using such paper.

Micro-encapsulation is the process of coating materials in the form of small spheres or capsules (diameters of about I to 200 microns) with natural or synthetic polymeric materials, such as polymethylmethaacrylate. The coating retains the contents in finely divided state, in each separate sphere, until such are released for use by rupturing the capsule walls, which can be by mechanical means, such as pressure, or by application of heat, such as by exposure to radiant energy. The incorporation of the compounds of this invention into the coating makes the wall more sensitive to rupture by exposure to infrared radiation thereby requiring less exposure time or lower intensity infrared radiation to effect rupture. Also, by use of different amounts of these compounds in the coatings of different capsules, such capsules can be made to rupture on absorption of different amounts of radiation, thereby producing a record of the relative quantities of infrared radiation impinging on any areas containing mixtures of such capsules.

Additionally, these compounds can serve to magnify the effects of infrared radiation falling on sensing elements when such elements are coated with such compounds simplifying amplification circuitry to convert signals from such elements to useable currents or voltages. Thus, sensors for fire detection devices may be so treated to make them more sensitive to the presence of flames. Also, sensors in data processing machines may be so treated to make them more sensitive to heat effects where such are used to operate electrical circuits.

In the third area of use, these compounds function by a miscellaneous assortment of mechanisms. Included in this category are such applications as incorporating these compounds into colored inks for use in ball-point or other pens so such inks will reproduce by those processes, such as Thermofax," which rely on infrared absorption by the ink on the document being copied. At present, carbon black must be used, limiting the inks for such purpose to black inks. Also incorporation of such compounds into face creams and dyes for clothing and other fabrics can serve to render the wearer invisible to infrared detection devices, such as the Sniperscope or Snooperscope" which operate by reflection of infrared radiation from the object, e.g., soldiers, tents, netting overguns, etc., to be detected back to a detector. Further, incorporation of such compounds into the paints used to cover non-luminous radiating surfaces, such as steam or hot water radiators, radiant heating wall, floor, or ceiling panels, etc. can serve to increase the efficiency of radiation of heat energy from such bodies to the enclosure surrounding them even though the paints are light in color or contain metal pigments.

Since growth rate of plants is sensitive to the wave lengths of incident light, interposition of a film or sheet containing these compounds between such plants and the radiant energy source can serve to modify this rate. For example, germination of lettuce seeds, and the like, is promoted most at about 650 millimicrons and is inhibited most at about 730 millimicrons. By suitable selection of these compounds and concentration in such film or sheet, substantially all the radiation at 730 millimicrons can be absorbed while a high proportion of that at 650 millimicrons can be transmitted to these plants to max imize the rate of germination.

The foregoing merely indicates some of the numerous uses for these compounds. From this listing and the properties of these compounds discussed elsewhere herein, many other uses for these compounds will immediately become apparent.

The invention will be further illustrated in conjunction with the following examples. Therein, unless otherwise noted, all parts and percentages are by weight and all temperatures are in degrees Centigrade.

EXAMPLE I N,N,N,N'-Tetrakis(p-Nitrophenyl)-p-Phenylenediamine A mixture of 10.8 parts (0.1 mole) of p-phenylenediamine, 94.5 parts (0.6 mole) of p-nitrochlorobenzene, 31.7 parts (0.23 mole) of potassium carbonate and 2 parts of copper powder are stirred and refluxed for 4 days in parts dimethylfonnamide. The mixture is then filtered and the solid washed well with dimethylformamide, water, acetone and then dried. There is obtained about 37 parts (59%) of redbrown solid, mp. 387390 C. An eight fold run gave a 76% yield of product melting at 390 C. After recrystallization from nitrobenzene, a sample had a melting point of 390392 C., and the following analysis:

Calcd for C H N O C, 60.8; H, 3.4; N, 14.2

Found: C, 60.7; H, 3.5; N, 13.9

EXAMPLE 2 N,N,N,N-Tetrakis(p-Aminophenyl )-p-Phenylenediamine A mixture of 29.6 parts (0.05 mole) of N,N,N',N"- EXAMPLE6 tetrakis(p-mitrophenyl)-p-phenylenediamine (from Example 1), 1 part of 10% palladium-on-carbon catalyst and 100 parts N,N,N',N'-Tetrakis(p-di-n-Butylaminophenyl)-p-Phenof dimethylformamide is hydrogenated at 90 C. in a ylenediamine hydrogenation autoclave until the theoretical pressure drop is The procedure of Example 3 is followed substituting an obtained. The mixture is filtered and the filtrate is poured into 10 equivalent amount of n-butyl iodide for the ethyl iodide. The 300 parts of water. The solid which separates is recrystallized product melts at 9294 C. The analysis follows.

from an ethanol-dimethylformamide mixture, giving about Calcd for C H N z C, 80.8; H, 10.1; N, 9.1

parts (64%) of purified product, melting about 300 C., and Found: C, 81.1; H, 9.6; N, 9.3 having the following analysis. Calcd for C H N C, 76.2; H, 5.97; N, 17.8 15 EXAMPLE 7 (mm 76 5 17 8 N,N,N',N'-Tetrakis(p-Dioctylaminophenyl)-p-Phenylenediamine EXAMPLE3 The procedure of Example 3 is followed substituting an N N p Diethylaminophenyl) p Phen equivalent amount of octyl iodide for the ethyl iodide. ylenediamine A mixture of 14.2 parts (0.03 mole) of N,N,N,N'- EXAMPLE 8 tetrakis(p-aminophenyl)-p-phenylenediamine (from Example 2), 56.2 parts (0.36 mole) of ethyl iodide and 33.1 parts (0.24 N,N,N',N'-Tetrakis(p-Didodecylaminophenyl)-p-Phenmole) of potassium carbonate is stirred and refluxed for four ylenediamine nHz5)N]--N- '"E u 2s)2] 2 '2 hours in 200 parts of 80% aqueous acetone. The mixture is The procedure of Example 3 is followed substituting an then cooled and filtered. The solid collected is washed with equivalent amount of dodecyl bromide for the ethyl iodide.

water, dried, and then recrystallized from dimethylformamide-ethanol mixture. The product is obtained as a yellow- 40 MPL green solid, m.p. 2l4-2l5 C. It analysis follows. EXA E 9 Calcd for 0 mm,: c, 79.3; H, 8.7; N, 12.1 N, k (py p yl)-p- Found: C, 79.2; H, 8.7; N, 12.0 y enedi m ne EXAMPLE 4 The procedure of Example 3 is followed substituting 18.7

parts (0.12 mole) ofethyl iodide and 16.6 parts (0.12 mole) of TetraklflpDlmflhYlammoPhenflyp'Phen' potassium carbonate for the amounts used therein.

ylenediamine 1 (CHIOQN ----N-- -N- N(CH )2 Q1. L

The procedure of Example 3 is followed substituting 3.1; EXAMPLE l0 equivalent amount of methyl iodide for the ethyl iodide. The product melts at 271273 C. The analysis follows. N,N,N',N'-Tetrakis(p-Nitrophenyl)Benzidine 1 Q Q K2 1 o N N--- -NO i Calcd for C H N C, 78.0; H, 7.5; N, 14.4 A mixture of 9.2 parts (0.05 mole) of benzidine, 47.3 parts Found: C, 77.2; H, 7.7; N, 14.5 (0.3 mole) of p-nitrochlorobenzene, 16.6 parts (0.12 mole) of anhydrous potassium carbonate, 1.0 part of copper powder EXAMPLE 5 and parts dimethylformamide is stirred and refluxed for NNNIN, Ten,akis(p di n propylaminophenyl) p phen four days. The mixture is then filtered, washed well with ylenediamine dimethylformamide, water, and acetone, and dried. About The procedure of Example 3 is followed substituting an 24.0 parts of an orange powder is obtained (71% yield). Meltequivalent amount of n-propyl iodide for the ethyl iodide. The ing point 370-374 product melts at l57l 58 C. The analysis follows. Calcd for c ri m; c, 80.2; H, 9.5; N, 10.4 EXAMPLE 11 Found: C, 8 H, 109 75 N,N,N',N'-Tetrakis(p-Aminophenyl)Benzidine A mixture of 24.0 parts (0.035 mole) of N,N,N',N- The general procedure of Example 13 is followed, except tetrakis(p-nitrophenyl)benzidine (from Example 10), 1 part 5 that equivalent amounts of N,N,N',N'-tetraphenyl-p-phenof palladium-on-carbon catalyst and 100 parts of ylenediamine and silver hexafluoroantimonate are substituted dimethylformamide is hydrogenated at 80 C. in a hydrogenafor the N,N,N',N'-tetrakis (p-diethylaminophenyl)-p-phention autoclave until the theoretical pressure drop is observed. ylenediamine and silver hexafluoroarsenate, respectively.

The mixture is filtered and the filtrate is diluted with 300 parts Similarly effective infrared absorbing compounds may be of water. The solid which separates is recrystallized from a 10 prepared after the fashion of Example 14 by utilizing as a mixture of dimethylformamide and ethanol, giving about 1 L2 starting reactant, in place of the N,N,N',N'-tetraphenyl-pparts (55% yield) of product, melting at 313-316 C. pehnylenediamine, substituted N,N,N',N'-tetraryl arylene Calcd for C H N C, 78.8; H, 5.84; N, 15.3 diamines where the substituents are present on the aryl nuclei. Found: C, 77.9; H, 5.90; N, 16.7 1 5 Thus, substituents, such as alkyl (methyl, ethyl, propyl, butyl,

etc.), alkoxy (methoxy, ethoxy, butoxy, etc.), aryl (phenyl), alkaryl (tolyl), and acyl (acetyl, etc.) may suitably be present EXAMPLE 12 without adversely affecting the infrared absorbing power of N,N,N,N'-Tetrakis( P-diethylaminophenyl) benzidine the product compound.

EXAMPLE l5 A mixture of 11.0 parts (0.02 mole) of N,N,N',N'- A series of aminium compounds of the above formula are tetrakis(p-aminophenyl)benzidine, 37.4 parts (0.24 mole) of prepared by the general procedure of Example 13 using the ethyl iodide, 22.1 parts (0.16 mole) of anhydrous potassium appropriate N,N,N,N'-tetrakis( p-dialkylaminophenyl)-pcarbonate. and 160 parts of 80% aqueous acetone is stirred phenylenediamine and silver salt. and refluxed for 5 hours. The mixture is cooled and filtered, and the solid is washed well with water and then with acetone R X and dried. The product is recrystallized from hot dimethylformamide to give a solid, about 9.5 parts (62% yield), melting 8. CH ASP point 213-2l4.5 C. b. CH SbF Calcd for C H N z C, 80.83; H, 8.29; N, 10.88 0 51g E Q Found: C, 78.21; H, 8. 14; N, 11.49 LE h f. n-C H e g. i'|C,, -I, G h. nC.H, EXAMPLE 13 i. C l-I, SbF. j. C I-l SbF, B!S( p-D1ethylamrnophenyl)[ N ,N-B1s-( p-Diethylaminophenyl)-p- Aminophenyl1Aminium Hexafluoroarsenate l The filtrate is diluted with an equal volume of ethanol.

Q 1 1 CQH 1N ---N-- N---- N C H A F a) 2 L (n2 s)2 2 S 0 To a solution of 3.49 parts (0.005 mole) of N,N,N,N'- EXAMPLE l6 tetrakis(p-diethylaminophenyl)-p-phenylenediamine (Product of Example 3) in 25 parts of hot dimethylformamide Bis(p-Ethylaminopheny){N,N-Bis(p-Ethylaminophenyl)-pis added 1.49 parts (0.005 mole) of silver hexafluoroarsenate Amino-phenyl]Aminium Hexafluoroarsenate in 25 parts of dimethylformamide. After stirring for one-half The procedure of Example 13 is repeated substituting an hour, the mixture is filtered and the filtrate diluted with 350 equivalent amount of N,N,N',N'-tetrakis(p-ethylaminophen' parts of ether. On cooling in dry-ice-acetone mixture the yl)-p-phenylenediamine (Product of Example 9) for the product separates. There is obtained about 3.5 parts of green N,N,N',N-tetrakis(p-diethylaminophenyl)-p-phensolid melting at 18 9-185 C. ylenediamine.

EXAMPLE 14 EXAMPLE l7 Diphenyl-(N,NDiphenyl-p-Aminophenyl)Aminium Hex- Bis(p-Diethylaminophenyl){N,N-Bis(p-Diethylaminophenyl)- afluoroantimonate 4'-Aminobiphenylyl]Arninium Hexafuoroarsenate To a solution of 0.77 parts (0.001 mole) of N,N,N,N'- To a solution of 47.3 parts (0.1 mole) of teuakis-(4- tetrakis(p-diethylaminophenyl)benzidine (Product of Examaminophenyl)-p-pheny1enediamine in about 200 parts of p in 40 P8118 Ofacelone is added r pwi e wi h Iirringa acetic acid there is added 70.4 parts (0.16 mole) of liquid solution of 0.30 parts (0.001 mole) of silver hexafluoroarethylene oxide at 10 C. The mixture is stirred and allowed to senate in 5 parts of acetone. After stirring for about 5 minutes 5 warm to room temperature at which point an exotherm takes the mixture is filtered and the filtrate diluted with 200 parts of place. The reaction mixture is then stirred and cooled from ethyl ether. On cooling in dry-ice-acetone, a green solid time to time so as to maintain a gentle reflux at about 65 C. 5617a! ates, P p duct. from the heat of reaction. After an additional stirring period of 3 hours at room temperature, the reaction mixture is diluted EXAMPLE 18 with about 400 parts of water followed by sufficient dilute Two aminium compounds of above formula are prepared by sodium hydroxide to give a positive test on phenolphthalein the procedure of Example 16 substituting an equivalent indicator paper. The product is separated by filtration, washed amount of the appropriate silver salt for the silver hexwith water and recrystallized from aqueous alcohol. The puafluoroarsenate as shown be rified product (about 60 parts) melts at 190-192 C.

Compound X 20 Analysis-Calc'd. for CMHWNGO: N. 10.2 Found: N, 10.0

a. C10 b. SbF: Part (B) Bis( 4-[bis(2-Hydroxyethyl )Amino lPhenyl) [N ,N-bis( 4-[ bis(2-Hydroxyethy1)Amino]Pheny1)-4-Aminopheny1]Amini- EXAMPLE 19 um Hexafluoroantimonate A series of aminium compounds of the above formula are To a solution of 3.3 parts (0.004 mole) of N,N,N,N- prepared by the general procedure of Example 13, using the tetrakis(4-[di(2-hydroxyethy1)amino]phenyl)-p-phenappropriate N.N,N',N'-tetrakis (p-substituted aminophenyl)- ylenediamine (product of A, above) in parts of methanol is p-phenylenediamine and silver hexafluoroantimonate. The added 1.37 parts (0.004 mole) of silver hexafluoroan- N,N,N,-N'-tetrakis (p-substituted aminophenyl)-p-phen- 40 timonate. After stiring for 1 hour, the mixture is filtered and ylenediamine is prepared by reacting tetrakis (p-arninophenthe residue is washed with methanol. The combined filtrates y1)-p-phenylenediamine (from Example 2) with the apare diluted with ether and cooled in a dry-ice-acetone bath. propriate alkyl or acyl halide by the procedure of Example 3 The solid which separates is collected by filtration, washed or Example 9. with petroleum ether and dried. After 3.3 parts of a watersoluble green solid is obtained, decomposing at 121-6 C. R R

1 Example 21 g 5 3%}: C H CH Bis(4-[bis(2-1-1ydroxyethy1)Amino]Phenyl)N,N-bis(4- OLCSHSHHCH: Z Z [bis(2Hydroxyethyl)Amino]Phenyl)-4-Aminophenyl)Aminid. l-naphthylmethyl l-naphthylmethyl um Nitrate I f 1' [(HOCH OHg)zj--N-- --N---L-N(CH CH OH)g] NO;-

e. CH, CHCl-b- H, H lt- The procedure of Example 20 (B) is followed substituting H 0.68 part (0.004 mole) of silver nitrate for the silver hex- P FCGH4CH2 afiuoroantirnonate. The product is a water-soluble green solid i. CF,CH, H (about 3.0 parts) decomposing at l75-l 77 C. j. c n H m qmcuz H EXAMPLE 22 l. C6H5CH=CHCH: 1-

P n (A) Analysis indicates that three of the sulfonic acid groups are present as NiNiNQNITetrakiqPDiethylaminophenyl)'mphen the sodium salt and the fourth sulfonic acid group serves as the anion ylenediamine (X') in the above formula.

Phenyl tetrakis(p-aminophenyl)-m-pheny1enediamine (Product of Part(B) Bis(p-Diethylaminopheny1)[N,N-bis(p-Diethylaminophenyl)- m-Aminophenyl1Aminium l-lexafluoroantimonate To a solution of 0.732 part (0.00105 mole) of N,N,N',-N'- tetrakis(p-diethylaminophenyl)-m-phenylenediamine (product of A, above) in 25 parts of acetone is added 0.343 part (0.001 mole) of silver hexafluoroantimonate. After stirring for 3 hours at ambient temperature, the mixture is filtered and the filtrate is evaporated. The residue is the desired product.

Spectral absorption curves of organic solvent solutions of salts of this invention were determined in the visual and near infrared regions at from 0.35 to 2.00 microns. For this purpose a recording spectrophotometer fitted with a near-infrared attachment and a tungsten light source, is used. The wavelength of maximum absorbance (A max.) is determined from the curve. Absorptivity at the wavelength of the maximum absorption, designated (a is an expression of the degree of absorption. It is calculated using the following relationship:

max. g a/ wherein a absorptivity b the thickness of the cell (spectrophoto meter) in cm.

c the concentration in grams per liter T= transmittance of light passing through the solution T transmittance of light passing through the solvent in the same cell EXAMPLE 23 In accordance with the foregoing discussion, spectral absorption curves of the solutions of aminium salts of Examples 13-19 and 22 in acetone and of Examples 19k, 20 and 21 in water were determined in the visual and near infrared regions at from 0.35 to 2.00 microns. The results are shown below. It will be noted that there are two absorption peaks in the nearinfrared region for the phenylenediamine derivatives of Examp1es13,15a-15h,19a-19eand19h-19l.

Absorption Max "Kg. 1460 14.1 980 26.0 410 16.4 15h. 1420 13.8 980 23.1 415 16.4 17 1050 31.9 610 3.3 400' 24.8 18a. 1050 21.0 610 2.6 365 35.0 18b. 1055 24.1 600 2.6 365 31.6

1911. 1330 15.7 835 11.9 405 16.4 191;. 1400 12.8 870 10.8 410 12.4 19c. 1420 13.5 870 11.4 415 12.8 19d. 1410 10.0 865 8.7 410 100 19a. 1400 17.4 880 16.1 415 17.9 19]. 960 8.2

(l)= not A max. 2) solvent was water.

EXAMPLE 24 Spectral absorption curves of solutions of the product of Example 13 in three solvents are obtained.

Example No. A (my) 5 5 400 19,9 15a. 1325 19.2 930 18.9 410 19.5 1511. 1310 15.6 970 16.0 410 16.4 15v. 1450 18.7 930 21.3 414 19.3 15d. 1440 20.7 950 24.1 415 21.7 15s. 1460 18.4 950 20.5 415 18.6 15]. 1460 17.1 950 19.4 415 17.7

acetate film by casting an acetone solution of the plastic and the additive on plate glass. These thin films exhibit strong near-infrared absorption having peaks at 1,450 and 950 millimicrons. The light stability of the additive during exposure in an Atlas Fade-Ometer is measured spectrally. Curves are Additive Remaining F ade-Ometer Exposure (hours) poly(methyl methacrylate) films in the manner described in Example 20 for cellulose acetate. The films show intense nearinfrared absorption with peaks at 1,450 and 950 millimicrons. The light stability of the additive is measured.

Hours of Fade-Ometer Exposure Additive Remaining EXAMPLE 27 The product of Example 13 at a concentration of 0.10% (on weight of plastic) is incorporated into poly(methyl methacrylate) molding powder by fluxing on steam-heated roll mills. Chips, 74 mils in thickness, are compression molded. A transmission curve of the chip shows that the additive functions as a very effective near-infrared barrier while transmitting a considerable amount of visible light.

Wavelength (Millimicrons) Transmittance EXAMPLE 28 The stability of the product of Example 13 during prolonged exposure to high temperatures is measured using methyl salicyate as a high boiling solvent. Dilute solutions of the additive are heated in an oil bath at various temperatures. The percent additive remaining is measured spectrally.

Temperature=200C. Temperature=2 10C. Heating Time Additive Heating Time Additivei (mins.) Remaining (mins.) Remaining EXAMPLE 29 The heat stability of the product of Example 13 in a poly(methyl methacrylate) is measured as follows: Films containing 0.32% of additive (on weight of plastic) are cast on plate glass from an acetone solution of the polymer and additive. The films are dried for several hours at 70 C. to remove the solvent. A curve of the cast film is obtained. It is assumed that no decomposition occurs during this mild heat treatment. Sections of the cast film are compression molded between electrically heated plates at various temperatures. Curves of the compression molded chips are compared to the cast film to determine the percentage of additive lost on heating.

1. A compound of the formula:

wherein R is selected from allyl, benzyl and alkyl of one to 12 carbon atoms; R is selected from ally], benzyl, alkyl of one to 12 carbon atoms and hydrogen and n is an integer of from 1 to 2; provided (a) that when n is l and R is allyl, benzyl or alkyl, then R is the same as R, (b) that when n is 1 and R is hydrogen, then R is ethyl, and (c) that when n is 2, then both R and R are ethyl.

2. N,N,N',N-Tetrakis(p-diethylaminophenyl)-p-phenylenediamine.

3. N,N,N',N-Tetrakis(p-diethylaminophenyl)-benzidine.

4. N,N,N',N'-Tetrakis( pdibenzylaminophenyD-p-phenylenediamine.

5. N,N,N',N-Tetrakis(p-dibutylaminophenyl)-pphenylenediamine. 

2. N,N,N'',N''-Tetrakis(p-diethylaminophenyl)-p-phenylenediamine.
 3. N,N,N'',N''-Tetrakis(p-diethylaminophenyl)-benzidine.
 4. N,N,N'',N''-Tetrakis(p-dibenzylaminophenyl)-p-phenylenediamine.
 5. N,N,N'',N''-Tetrakis(p-dibutylaminophenyl)-p-phenylenediamine. 